Recording apparatus having a mechanism for securely installing the proximal end of a recording pen to a drive shaft of a pen motor for purposes of oscillating and driving the recording pen, has been generally known. An example of such recording apparatus is illustrated in FIG. 3, where a pen-holder 3 is installed over the center of a drive shaft 2 of a pen motor 1 via an installation hole 3a. In such prior art recording apparatus, a resilient plate 6 is provided at a proximal end of a recording pen 5 by means of two screws 4, which are secured to the upper surface of this pen-holder 3. The resilient plate 6 is arranged such that adjustment of its height is effected by means of an adjustment screw 7 screwed into the pen-holder 3. A cutout 3b communicating with the installation hole 3a is formed in a radial direction in one side of the pen-holder 3. A threaded hole 3c is provided in the pen-holder 3 perpendicular to this cutout 3b, and an installation screw 8 is screwed into this threaded hole 3c. Thereafter, as installation screw is tightened, the pen-holder 3 is secured to the drive shaft 2. Notably, an ink supply port denoted by reference number 9, is provided for supplying ink to a distal end of the recording pen 5.
In order to install the recording pen 5 and pen-holder 3 sub-assembly to the drive shaft 2 of the pen motor 1, pen-holder 3 is first mounted onto the drive shaft 2, and then recording pen 5 and pen-holder 3 sub-assembly is positioned so that the recording pen 5 is disposed perpendicular with respect to reference line 10 of the pen motor 1. In such an arrangement, the "pen installation angle" of the recording pen 5 with respect to the reference line 10 of the pen motor 1 is 90.degree., as desired.
In order for the recording apparatus to function properly, it is essential that the recording pen 5 be accurately installed in a perpendicular manner with respect to a reference line 10 of a pen motor 1. However, using the above-described conventional pen installation device, a serious problem arises. Specifically, when the installation screw 8 is tightened to secure the pen-holder 3 to the drive shaft 2, the recording pen 5 (being accurately positioned in advance) is liable to, and typically does move with respect to reference line 10, and as a result, an error in the installation angle of the recording pen 5 occurs.
Thus, there is a great need for a simple recording pen installation mechanism which prevents the recording pen from rotating with respect to the reference line of the pen motor, as the installation screw is tightened, and also, a mechanism which provides secure mounting of the pen with respect to the drive shaft of the pen motor. As the prior art has failed in this regard, errors in "pen installation angles" occur often, thereby affecting the overall performance of the recording apparatus of which the recording pen is only a part.